Protruding electrodes called bumps are in some cases used as connecting devices to mount electronic parts on a substrate. The protruding electrodes are formed by depositing solder over electrodes provided on the substrate. For example, BGA (Ball Grid Array) connection structures are used to mount electronic parts on a substrate. In the structure, the protruding electrodes are regularly arrayed by depositing solder over electrodes regularly arrayed on the substrate.
An output terminal of a semiconductor integrated circuit has been disclosed. The output terminal is used to determine whether the protruding electrodes and the electrodes are normally connected. Related-art techniques are disclosed in Japanese Laid-open Patent Publication No. 9-82714.
If the connecting devices are damaged to cause connection failures, transmission of signals is interrupted, resulting in breakdown of an electronic apparatus incorporating the substrate. Accordingly, whether or not the connection of the connecting devices is in a proper condition is desired to be detected as accurately as possible. Furthermore, if there is a possibility of a connection failure, it is advantageous to know the possibility in advance.